Stevia rebaudiana is a plant species in the sunflower (Asteraceae) family, which has naturally sweet leaves. The active compounds that impart the sweet flavor to stevia leaves are steviol glycosides. The most common steviol glycosides are stevioside and rebaudioside A, both of which have up to 250 to 400 times the sweetness of sugar. Stevioside tends to be more prevalent in unimproved lines of stevia leaves than rebaudioside A. The development of new varieties of Stevia rebaudiana with higher levels of rebaudioside A than stevioside is desirable for use as a sugar substitute.
The present invention relates to a new and distinct variety of Stevia rebaudiana, the ‘SW 227’ line, which has high plant vigor characterized by extensive stooling and branching; an excellent sweet leaf taste with very low bitterness and aftertaste; and leaves having an average rebaudioside A content of 10.7%. Table 1 provides averaged stevioside data for samples of the dry leaves of the ‘SW 227’ line.
Plant Vigor: The ‘SW 227’ line was found to have much greater stooling (branching from the ground) and much greater branch numbers in comparison to the majority of the plant population from which the line was derived.
Leaf Taste: The leaves of the ‘SW 227’ line were found to have an excellent sweet taste in comparison to a majority of the plant population from which the line was derived and very little bitterness and aftertaste in comparison to most stevia varieties.
Dry Leaf Yield: The ‘SW 227’ line producing 5500 kg/ha (˜4907 lb/ac) of dry leaf yield based on six months growth (April to September) at Ontario, Oreg., USA in 2015.
Rebaudioside A content: In 2015, the leaves of the ‘SW 227’ line were found to have a high percentage of rebaudioside A at 10.7% (Table 1).
Stevioside content: The leaves of the ‘SW 227’ line were found to have a low percentage of stevioside at just 1.4% (Table 1).
Steviol Glycosides: The leaves of the ‘SW 227’ line were found to have high levels of total steviol glycosides at 13.3%, with rebaudioside A accounting for 80.4% of the total steviol glycoside content in the leaves (Table 1).
Ratio of rebaudioside A to stevioside content: The ratio of rebaudioside A to stevioside in the leaves of the ‘SW 227’ line was found to be high at 7.6 (Table 1).
TABLE 1Dry Leaves‘SW 227’Percentage of rebaudioside A10.7%Percentage of stevioside1.4%Percentage of total steviol glycosides13.3%Ratio of rebaudioside A:stevioside7.6Percentage of rebaudioside A to total steviol glycosides80.4%
The ‘SW 227’ stevia line was asexually reproduced from root cuttings derived from a single Stevia rebaudiana plant that was selected on Oct. 5, 2014, at Ontario, Oreg. and which was grown outdoors under full sunlight. The parent plant was grown in 2013 from seed derived from a cross between the Stevia rebaudiana clone known as ‘selection 395’ (unpatented) and the ‘SW 129’ stevia line (U.S. Plant Pat. No. 28,373).
The selection of the ‘SW 227’ line was based on evaluations of plant vigor, particularly plant stooling and branching; leaf taste; and rebaudioside A content.
The 2015 leaf harvest period in Ontario, Oreg. for the ‘SW 227’ line was a single harvest in the fall or multiple harvests throughout the summer to early fall. Plant yield and leaf quality of the ‘SW 227’ line was confirmed throughout 2015 in Ontario, Oreg.